Wearable Robot Weight Reduction via Single Knee Drive Unit
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Solution Overview
Problem
Wearable robots for assisting lower extremity muscular strength face challenges in reducing weight and complexity, leading to excessive load on users, particularly in work site applications, due to the use of active joints and drive units across all joint parts.
Innovation Solution
A wearable robot design with a reduced weight and simple structure, featuring a central securing part, hip and knee joints with passive and active components, and an ankle part with elastic support, where the drive unit is only in one joint, distributing the weight to the ground through rigid fastening members and elastic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drive units are installed in all joint parts of the wearable robot, then the robot can provide active assistance at each joint, but the weight of the robot increases excessively and the configuration becomes complex
Solution Approach 1:
The patent extracts drive units from all joint parts and concentrates them in only one joint part. Specifically, the drive unit is installed exclusively in the knee joint part, while the hip joint part uses a passive structure without active drive mechanisms. This extraction of unnecessary drive units from the hip joint directly reduces robot weight while maintaining assistance capability where most needed.
Solution Approach 2:
The single drive unit in the knee joint part serves multiple functions: it provides active assistance for knee movement, drives the entire lower extremity mechanism through the linkage system, and enables both hip and knee joint assistance indirectly. This multi-functionality allows one drive unit to replace what would traditionally require multiple separate drive units.
2Reliability
If drive units are installed in all joint parts of the wearable robot, then the robot can provide active assistance at each joint, but the configuration becomes complex and malfunction frequency increases
Solution Approach 1:
The patent removes drive units from the hip joint part, leaving only a passive mechanical linkage structure. This extraction simplifies the overall configuration significantly, reducing the number of controlled components from multiple drive units to a single drive unit in the knee joint, thereby reducing potential failure points and control complexity.
Solution Approach 2:
The patent segments the control and actuation functions, concentrating all active control in the knee joint while the hip joint operates passively through mechanical linkage. This segmentation separates the complex controlled system (knee with drive unit) from the simple mechanical system (hip without drive unit), making the overall configuration more manageable and less prone to malfunction.
3Reliability
If a wearable robot is designed to assist lower extremity strength, then it can help users with muscular weakness, but it exerts excessive load on the user's lower extremity when carrying high loads
Solution Approach 1:
The patent employs an ankle weight that acts as a counterweight to offset the load on the user's lower extremity. The ankle weight, combined with the elastic member, creates a balancing force that compensates for the robot's own weight and any additional carried loads, thereby reducing the net force that the user's lower extremity must support.
Solution Approach 2:
The elastic member acts as an intermediary between the ankle weight and the lower extremity. It absorbs and distributes forces, providing a cushioning effect that reduces peak loads on the user's joints and muscles while still allowing the robot to provide necessary assistance during movement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design significantly reduces the weight applied to the user, minimizes drive unit usage, and decreases malfunction frequency, resulting in a more reliable and cost-effective system with simplified control logic.
Implementation Method 1
an elastic member connected to the ankle part by an elastic support member to transfer a weight of the robot and an added weight to the ground
Implementation Method 2
the femur part may have elasticity and may be a four-bar linkage including a spring damper
Data Source
AI summary
A wearable robot for assisting muscular strength of the lower extremity of a user: The wearable robot can be worn on user's legs and includes a central securing part, a hip joint part hingably coupled to either side of a lower end of the central securing part, a femur part fastened to the hip joint part and having rigidity, a knee part including an outer frame and a knee assistant, and a drive unit fastened to one of the hip joint part and the knee joint part to allow operation of the joint part. The outer frame includes an upper side outer frame fastened to a lower end of the femur part and a lower side outer frame fastened to the upper side outer frame by a rotatable knee joint part Both the upper side outer frame and the lower side outer frame are fastened to the knee assistant worn by the user.